Disclaimer: I do not own Ao no Exorcist.
"Black takes bishop," Mephisto thought long before Shiro could place a finger on the black rook. He gave up counting the number of times he had seen the same move, the same gameplay, and—eventually—the same conclusion once he reached the twentieth repetition. Indeed, Shiro commanded his hand as Mephisto predicted—no, known from his other lives, if he chose to call them such. He stared at the board with eyes that saw nothing before them, his hand moving towards his queen like one of Pavlov's dogs—salivating upon hearing the bell and conditioned to do the same thing given the same stimulus over and over again as if it was created for this sole purpose.
"Mephisto—"
"Check."
He recognized the desperation in the priest's voice, but the demon refused to meet Shiro's eyes, not wanting to confirm what he already knew.
"Mephisto, please...!"
Shiro's voice wavered, but Mephisto continued to stare through the chess pieces as if they were transparent, words kept in his mind. Going through the same scene more times than he would bother remembering drained his counter-arguments—and will—faster than a demon sucking the soul out of its victim.
"MEPHISTO!"
He heard the chair hit the floor even though the world they were in was nothing but a void, and in this void objects fell soundlessly on emptiness. His eyes stayed unfazed despite seeing the checked board falter and the chess pieces collapse into disarray upon meeting Shiro's fists.
Stop. Mephisto wanted to plead, but the word remained a mere thought.
"Please..."
The demon king shut his eyes as a teardrop not his landed on the black knight lying on its side, the horse's crystal eyes accusing him like a ghost haunting its murderer. Without him looking, he knew it did not end with a single drop.
"Samael..."
Stop it, Shiro.
For once he wished ignorance to something—to the words that would follow and to the implications they had in tow—but he had heard the same request in far too many worldlines that he began to think it was pointless to object.
"Please save my children..."
He held back a sigh of resignation as what he dreaded spilled from the priest's mouth.
I'm sorry. If only I…
A/N:
The next parts are longer. Unlike most fanfics involving Shiro and Mephisto, I'd like to imagine their friendship more than to speculate on anything romantic, so no ShiroxMephi (unless you squint really hard).
Just a bit of warning before you proceed: Mephisto might be a bit OOC in the first few parts.
(1) He's difficult to write to begin with (I apologize in advance should I get sloppy); part of his charm as a character in the original series is that you can't tell what's going on in his mind, so revealing some of that presents the risk of missing the mark or losing some of that charm.
(2) He's still confused by recent events haha.
(3) Nature vs nurture; his experiences will also shape who he becomes.
(4) The plot calls for him to be a bit different from what we know, at least until we get past "that point."
